This invention relates to novel hydrophilic polymeric materials which are water-insoluble and water-swellable and which can be shaped effectively both before and after curing economically by conventional processing techniques.
In many instances in the health field it is desirable to shape an article so as to accurately mimic a bodily cavity or so as to form a perfect fit for better comfort and biocompatibility. In most conventional methods a negative imprint is first formed by filling the cavity with moldable material, removing it from the cavity and subsequently using it to prepare a mold for molding the desired shaped article(s). This is quite costly and extremely time consuming, especially when suitable apparatus for preparing the mold is not at hand. Further, it is sometimes difficult to do, especially when the cavity opening is smaller than the parameters of the actual cavity. In some medical applications, as in the case of bone prosthesis, etc., it may be advantageous to form the final article in situ. This may be impossible with most thermosetting plastics or with other materials which cure to rigid, inflexible shaped articles and do not form a settable paste intermediate stage.
Further, it is known to treat wounds, especially burned tissue surfaces, with a settable paste which may have medicinally active ingredients therein. Such paste and procedures are described in U.S. Pat. No. 4,272,518 which utilizes a hydrophilic polymer and an inert, normally-liquid organic vehicle having a relatively high boiling point. The resulting paste possesses a setting time period no greater than about one hour, and a working time period which is sufficient to permit an operator (e.g., clinician, nurse, doctor) to apply the paste to the wound and thereby obtain an occlusive film dressing. The preferred polymer employed therein is 2-hydroxyethyl methacrylate polymer and the preferred solvent is polyethylene glycol of 400-800 molecular weight.
while representing an advance in the art, such materials can evidence certain disadvantages, e.g., they are not readily curable and thus do not provide long term stable physical properties such as shape retention when exposed to solvents.